package com.ptmall.app.net;


import android.util.Base64;

import com.google.gson.Gson;

import java.security.MessageDigest;
import java.security.spec.AlgorithmParameterSpec;
import java.util.Map;

import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;


public class AESCrypt {
    private final Cipher cipher;
    private final SecretKeySpec key;
    private AlgorithmParameterSpec spec;
    public static final String SEED_16_CHARACTER = "DaCheAPPAesKey";

    private static AESCrypt instance = null;

    public static AESCrypt getInstance() {
        try{
            if (instance == null)
                instance = new AESCrypt();
            return instance;
        }catch (Exception ex){
            return null;
        }
    }

    public AESCrypt() throws Exception {
        // hash password with SHA-256 and crop the output to 128-bit for key
        MessageDigest digest = MessageDigest.getInstance("SHA-256");
        digest.update(SEED_16_CHARACTER.getBytes("UTF-8"));
        byte[] keyBytes = new byte[32];
        System.arraycopy(digest.digest(), 0, keyBytes, 0, keyBytes.length);

        cipher = Cipher.getInstance("AES/CBC/PKCS7Padding");
        key = new SecretKeySpec(keyBytes, "AES");
        spec = getIV();
    }

    public AlgorithmParameterSpec getIV() {
        byte[] iv = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, };
        IvParameterSpec ivParameterSpec;
        ivParameterSpec = new IvParameterSpec(iv);

        return ivParameterSpec;
    }

    public String encrypt(String plainText) throws Exception {
        cipher.init(Cipher.ENCRYPT_MODE, key, spec);
        byte[] encrypted = cipher.doFinal(plainText.getBytes("UTF-8"));
        String encryptedText = new String(Base64.encode(encrypted,
                Base64.DEFAULT), "UTF-8");

        return encryptedText;
    }

    public String decrypt(String cryptedText) throws Exception {
        cipher.init(Cipher.DECRYPT_MODE, key, spec);
        byte[] bytes = Base64.decode(cryptedText, Base64.DEFAULT);
        byte[] decrypted = cipher.doFinal(bytes);
        String decryptedText = new String(decrypted, "UTF-8");
        return decryptedText;
    }
    public String getBase64(Map map){
        Gson gson = new Gson();
        String json = gson.toJson(map);
        String result = "";
        try {
            result =  AESCrypt.getInstance().encrypt(json);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return result;
    }

}
